Clijsters, who won the Australian Open last month for her fourth Grand slam title, only needs to reach the semifinals of the Open Gaz de France this week to overtake Caroline Wozniacki at the summit of women's tennis.
Clijsters plays Kristina Barrois of Germany in the second round on Wednesday.
The 27-year-old Clijsters said Tuesday that "it would be a nice accomplishment" but "I'm not going to be disappointed if I don't make it." Even if she is successful, Clijsters says the moment she first became No. 1 in August 2003 at age 20 would always mean more to her. The Belgian last held the top spot in January 2006.